ABSTRACT This Administrative Supplement for Collaborative Science will support a new research partnership (between Dr. Tracy Finlayson in Public Health, and Dr. Lourdes Martinez in Communication) and the addition of social network science applied to an existing bilingual (English/Spanish) Oral Health Behavior Social Support (OHBSS) scale validation grant, specifically for Mexican-origin young adults (ages 21-40 years old). Our proposed research will focus on collecting and analyzing egocentric social network data, using the results to validate the new social support scale, and identifying differences in the way social structures impact the target oral health behaviors of interest (oral hygiene, accessing dental care). This proposed study is complementary to the parent grant?s scale validation goals, bridges theories and methodological approaches, and adds a new level of validation to the new OHBSS scale. The Structural Influence Model of Health Communication will be used as a guiding framework. Social Network Analysis (SNA) is a compelling addition that naturally extends the social support focus. Our work will generate key input examining the social network structures that facilitate the transmission of effective social support in promoting oral health behaviors, and lead to future studies addressing oral health disparities among Mexican-origin individuals by providing insight into whom members of this population perceive receiving effective social support for oral health behaviors. Identifying these critical individuals within one?s social network may enhance the design and deployment of future oral health interventions that ultimately reduce oral health disparities, a goal that aligns with the mission of the National Institutes of Health. This one-year project will address three integrated research aims. Aim 1 will focus on collecting and analyzing egocentric network data using a sex-stratified and balanced subsample of 60 study participants (50% men, 50% Spanish language dominant, 50% single marital status) from both parent study sites (1 urban, 1 rural area in two counties in California along the US-Mexico border). These participants will complete a half-hour individual interview, in either English or Spanish, to collect network density data through a standard name-generation social network mapping approach. Aim 2 proposes to validate the OHBSS self- report scale responses through the identification of specific individuals in the participants? social networks. Specifically, convergent and discriminant validity with OHBSS scale responses will be examined. Aim 3 focuses on comparing modes of communication and influence on Mexican-origin young adult men and women?s oral health behaviors by family members, health providers, or others in the participants? social networks. Analyses will specifically focus on determining whether effects of network structure on oral health behaviors are differentially stratified by socio-demographic characteristics. Findings from the SNA data can then inform the development of interventions to promote oral health behaviors among Mexican-origin young adult men and women designed to reduce the unequal burden of oral health disparities.